Hurricane Lee: Messaging for NH

Good morning everyone! Now that a significant amount of uncertainty in the forecast has been eliminated over the past 48 hours (particularly the NW jolt in the track), let's go over what to expect and most-likely impacts:

  1. Headlines: The Tropical Storm Watch continues for coastal Rockingham & Strafford Counties. The NHC is expected to either replace this with a Tropical Storm Warning or drop the tropical headlines altogether.
  2. Lee's Track & Intensity: Hurricane Lee will continue marching north into the eastern Gulf of Maine by midday Saturday, then make a sharp right-hand turn into the Bay of Fundy overnight Saturday. This favors the eastern pocket (GFS/America & GDPS/Canadian blend) of the forecast guidance shown in my previous post here. Lee is expected to become an extra-tropical storm in the Gulf of Maine on Saturday. This transition is the dissipation of the symmetrical tropical structure of Lee into an asymmetrical cyclone with frontal structures, an expansion of the wind field, an incredibly powerful corridor of winds on its flank, and seclusion of warm air to the cyclone's center.
  3. Expected Weather & Impacts:
    1. Rain: Light rain will advance into southeast NH after sunset Friday. Steady rain continues overspreading most of the state during the day Saturday, with the most efficient tropical downpours confined along a line from Raymond to Laconia east to the Atlantic coastline. Flooding is not a concern at this time.
    2. Wind: Sustained winds will increase through the same window as rainfall, with speeds of 15-25 MPH statewide during the day on Saturday. Wind gusts will vary, however a 12-18 hour window of gusts between 35-50 MPH are expected in and east of the Monadnock Region & White Mountain spine. These gusts will be maximized near the coast & in any convective elements. Most of the state has experienced rainfall significantly above average this summer, which has led to completely saturated soils & weakened tree root systems. The combination of these saturated soils & persistent wind gusts above 40 MPH will increase the threat for power outages across eastern NH, though a significant number of outage jobs are not anticipated at this time.
    3. Coastal Flooding/Surge: Storm surge of 1-2 feet is expected along the immediate Seacoast, particularly in flood prone areas. In addition, coastal flooding from repeated high wave action (not from storm surge) is likely, particularly around the 6:52 AM high tide Saturday. The window for both ocean flooding mechanisms will be concentrated from late Friday through late Saturday. A safe comparison of potential flood impacts for folks along the coast will be to assess how your property is affected by the king tide cycle. Preparations/mitigation efforts using this comparison should include an allotment for another ~1-1.5 feet of water to cover the high tide/peak storm surge combination early Saturday. Some roadways immediately next to the water may become flooded. Beaches & dunes will undergo erosion, some of which may be significant.